The U.S. Postal Service plans to move out of its historic Riverside Avenue post office in downtown Spokane to cut costs, Spokane Postmaster Karen Fairlee said Monday.

“We’re just in the beginning of a two- or three-part process,” she said. “Like any other business that needs more money to keep operating, we need to show we’re able to cut costs.”

She said she doesn’t know where the office will relocate, but it will remain downtown. That move won’t occur until late spring 2012, or later, Fairlee said.

USPS administrators haven’t identified a short list of alternate downtown sites, she added. They’ll be looking for a location with parking and easy pedestrian access, Fairlee said.

The first phase of the move will be to eliminate postal carrier pickups at the downtown facility. About 26 carriers who handle 19 routes use the building, which is next to the federal courthouse. Fairlee said those carriers will be moved “before the snow flies” to the Liberty Park Post Office, 1602 E. Sprague Ave.

The building at the corner of Lincoln and Riverside has been downtown Spokane’s main post office for 102 years.

The postal service uses space on the first floor and a loading dock in the basement. Upstairs is the federal Bankruptcy Court and office space. In addition to the carriers, about 15 other postal service employees work in the branch.

One source of cost savings would be to reduce the number of post office boxes in a new space, Fairlee said. The old building has 1,600 boxes, including some that are substantial in size. Few people need large boxes, she said. At present the post office is renting just more than 1,000 of the boxes.

The postal service pays about $350,000 per year for a lease and support services to the General Services Administration. The GSA has said that lease is non-negotiable; the postal service has determined a less expensive option can be found somewhere nearby, Fairlee said.

GSA spokeswoman Stephanie Kenitzer said the GSA hasn’t been notified of the postal service’s plan.

Normally the GSA will lease that available space to another federal agency. But “as a last option” the GSA would lease to non-government companies or agencies, Kenitzer said.

The post office building recently had $2.3 million worth of upgrades funded by the 2009 stimulus act.

The postal agency has said it’s considering a number of steps to save money, including reducing delivery to five days per week and closing more than 3,000 branches nationwide.

The choice of ending Saturday delivery can only be approved by Congress, and so far no consensus has developed to take that step.

Among branches that could be closed to cut costs are the Parkwater, Hillyard and Dishman stations in Spokane.

Fairlee said it’s not a sure thing that those three offices will be closed. The USPS needs to look at how residents in those neighborhoods would be affected, she said.